After a little bit of thinking, I've finally figured out a DLC "roadmap" for All-Star Strife that I think could be interesting and fun.
Basically, I plan on having three DLC fighter jobs, with two fighters added per job. There aren't any requirements when it comes to submission - anyone (given they're from an indie game, of course) is on the table. However, this is where the twist comes in. After each job, every submitted fighter who doesn't get in is added to a "deconfirm" list, meaning nobody can resubmit them for future jobs. This way, people are encouraged to submit different characters, including characters they have a personal attachment to.
I'm not 100% sure of this idea, but I think it could lead to some creative and fun submissions.